Strategies for Establishing Ponderosa Pine Seedlings in a Repeatedly Grazed Area of the Navajo Forest in Arizona—20-Year Results

Reforestation in some areas of the Navajo forest is challenging because of intense grazing and vegetative competition. A study was initiated in 1989 to determine if disking the site to alleviate competition, planting ponderosa pine seedlings, and installing fencing for 10 years to exclude livestock would result in acceptable stocking. After 20 years, 36 percent of trees had survived and were growing at an acceptable rate for the low-moisture site conditions. This approach met the goal of establishing an understory stand before harvesting the overmature overstory trees. Furthermore, exclusion of livestock allowed for seedlings to become tall enough to reduce the risk of grazing damage when the area was reopened to grazing. In fact, reintroduction of livestock after 10 years resulted in reduced vegetative competition with no apparent effect on seedling growth or survival.